Tag: galaxies

Golden and gleaming, this convex mirror arrived last week at the Goddard Space Flight Center in Greenbelt, Md., where it will be mounted on the much-anticipated Webb telescope. When the telescope is up and running, sometime later this decade, the Webb will take the title of the most powerful space telescope ever built, ousting even the Hubble. The Boulder-built mirror’s color comes from a microscopic layer of gold, 1,000 times thinner than a human hair. The gold will help the telescope better reflect infrared light, making distant planets and the universe’s first galaxies easier to see.

Note: You may want to click the full-screen button down there and watch this in its full hi-def glory.

Ever wished you could float through space, drifting past stars and cosmic dust clouds? The largest-ever 3D map of the universe, shown in the video above, gives you a sense of what that might be like, though the bright dots surrounding you are not stars, but whole galaxies, and you’re not quite drifting, but ripping along at a quadrillion times the speed of light.

To get a sense of the speed, just look at those galaxies and remind yourself that each is home to hundreds of billions of stars like our own. And you can even see, as the video progresses, the distinctive soap-bubble arrangement of the universe’s galaxies, arrayed in closely packed groups around vast tracts of empty space.

The Sloan Digital Sky Survey produced the 3D map from newly released data collected during two years of a six-year project. Knowing the locations of over a million galaxies will help astronomers find out how dark matter and dark energy are affecting the visible universe.

In the meantime, we’ll just watch this video again. And again. And again.

For the first time, astrophysicists have created a computer simulation of the formation of a spiral galaxy like the Milky Way (above). Researchers at the University of California at Santa Cruz and the Institute for Theoretical Physics in Zurich modeled their galaxy, Eris, using a software platform called Gasoline, which allowed them to track the motion of 60 million particles of gas and dark matter for over 13 billion simulated years. Overall, the simulation required 9 months of number crunching on NASA’s Pleiades supercomputer, with supporting simulations on supercomputers at UCSC and the Swiss National Supercomputing Center.

Previous efforts to model spiral galaxies have failed, ending in disfigured galaxies with central bulges much too large for their disks, according to the researchers. But Eris’ bulge-to-disk ratio, stellar content, and other features fall in line with observations of the Milky Way. The researchers point to a realistic model of star formation as a key to Eris’ success—their high-resolution simulation allowed stars to form only in regions with a high density of particles, resulting in a more accurate distribution of stars. More than just a nice movie, the work supports the cold dark matter theory, which says that the gravitational interactions of dark matter drove the evolution of the universe. A paper detailing the Eris simulation will be published in an upcoming issue of the Astrophysical Journal.

Astronomers have just announced they have discovered what may be the most distant galaxy ever seen, smashing the previous record holder. This galaxy is at a mind-crushing distance of 13.2 billion light years from Earth, making it not just the most distant galaxy but also the most distant extant object ever detected!

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Named UDFj-39546284, the galaxy is seen as it was just 480 million years after the Universe itself formed! The previous record holder — which was announced just last October — was 13.1 billion light years away. This new galaxy beats that by 120 million light years, a substantial amount. Mind you, these galaxies formed not long after the Big Bang, which happened 13.73 billion years ago. We think the very first galaxies started forming 200 – 300 million years after the Bang; if that’s correct then we won’t see any galaxies more than about 13.5 billion light years away. Going from 13.1 to 13.2 billion light years represents a big jump closer to that ultimate limit!

Sometimes, distractions can be useful in themselves. That’s the message this week from the Planck space telescope, which has a mighty big mission: to take baby pictures of the universe. While it hasn’t yet accomplished that task, the preliminary disturbances that Planck scientists are now dealing with are yielding cosmic insights of their own.

Orbiting the Sun roughly 1.5 million kilometres from Earth, the Planck space-based telescope is scanning the sky for ultra-cold objects. Its instruments are chilled to just a tenth of a degree above absolute zero and are designed to pick up the faint microwave afterglow from the Big Bang, which scientists hope can tell them about the earliest moments of the Universe. [Nature News]

Planck was launched in spring of 2009 by the European Space Agency, and it’s still gathering data to complete its chart of this cosmic microwave background (CMB); researchers hope the map will shed light on the young universe’s brief “inflationary” period when it expanded extremely rapidly. At the moment, however, Planck is busy detecting other sources of microwaves so that it can subtract this “foreground” radiation from its map of the background.

More than a trillion pixels from a million-plus images, combined to create the most detailed map of the universe ever created—one that would require a wall of a half-million HDTVs to properly appreciate. Not bad for something that looks a little like tan carpeting.

What you’re seeing is about one-third of the sky, imaged by the Sloan Digital Sky Survey, which has been assembling images from Apache Point Observatory in New Mexico for more than a dozen years to image the cosmos in unprecedented detail.

It replaces an image that is now over half a century old, created on photographic plates by the Palomar Sky Survey in the 1950s but still used by astronomers today. It contains 10 times as many objects – such as galaxies, stars and nebulae – as the Palomar survey and scientists hope it will be used for decades to come by astronomers hunting for everything from dark matter to planets orbiting other stars. [The Guardian]

One of these things is not like the other: Astronomers have spotted a dwarf galaxy that spans just 3,000 light years across (as opposed to our Milky Way’s diameter of 100,000 light years), but hosts an outsize supermassive black hole for its puny size.

Some smaller galaxies have supermassive black holes as well, but in general these dwarf galaxies have some structure to them, with a well-defined core. Henize 2-10, as you can see, it a mess! It doesn’t have much overall structure, which is why it’s classified as an irregular galaxy. The thinking for big galaxies is that the black hole forms at the same time as the galaxy itself, and to regulate the growth of each other. When you look at lots of big galaxies, there’s a pretty clear overall correlation between the mass of the black hole and the galaxy around it.

So it’s pretty weird that Henize 2-10 has a supermassive black hole at all, but it turns out the hole is also about a million times the mass of the Sun — that’s pretty freakin’ big for such a tiny galaxy! That’s 1/4 the mass of our own black hole, in a galaxy that itself is far smaller than ours.

At the heart of most galaxies lies a supermassive black hole. And in some galaxies, the black hole is bigger and badder than usual. These raging overachievers, called active galactic nuclei, can be some of the brightest objects in space, sweeping up a huge amount of material from their local areas and emitting enough energy to outshine the galaxies around them. The question is, where do they get all the stuff to swallow? Not where scientists had expected, according to a new study.

An obvious answer—and the one that for years has seemed likeliest—is that these hyperactive black holes arise from the merger of galaxies. All the gas that comes together during a two-galaxy crash could feed a supermassive black hole, turning it from docile to brilliant. But there’s a problem.

“It’s totally intuitive,” said astrophysicist Knud Jahnke of the Max-Planck Institute for Astrophysics in Germany, a coauthor of the new study. “But it was a gut-feeling idea. In court you would say there was some circumstantial evidence for it, but no proof.” Earlier studies looked only at galaxies with the brightest active nuclei, which could have biased their results, Jahnke said. They also didn’t compare active galaxies to those with quiet black holes. [Wired]

For a study coming out in the Astrophysical Journal, Jahnke and others tried to put the galaxy merger hypotheses through a true controlled test, and they found no solid evidence to back it up.

A study by Yale astronomer Pieter van Dokkum just took the estimated number of stars in the universe—100,000,000,000,000,000,000,000, or 100 sextillion—and tripled it. And you thought nothing good ever happens on Wednesdays.

Van Dokkum’s study in the journal Nature focuses on red dwarfs, a class of small, cool stars. They’re so small and cool, in fact, that up to now astronomers haven’t been able to spot them in galaxies outside our own. That’s a serious holdup when you’re trying to account for all the stars there are.

As a consequence, when estimating how much of a galaxy’s mass stars account for – important to understanding a galaxy’s life history – astronomers basically had to assume that the relative abundance of red-dwarf stars found in the Milky Way held true throughout the universe for every galaxy type and at every epoch of the universe’s evolution, Dr. van Dokkum says. “We always knew that was sort of a stretch, but it was the only thing we had. Until you see evidence to the contrary you kind of go with that assumption,” he says. [Christian Science Monitor]

The record for the most distant object in the Universe ever seen has been smashed: a galaxy has been found at the staggering distance of 13.1 billion light years!

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It’s so dim that the faintest star you can see with your unaided eye is 4 billion times brighter. Its distance is simply numbing; the Universe itself is only 13.7 billion years old, so the light from this object began its journey on its way to Earth just 600 million years after the Universe itself formed.

Head to the full post at Bad Astronomy for all the details about how astronomers used the Hubble Space Telescope to find this faraway galaxy, and what the discovery tells us about the infant universe.